Provided is a resistance spot welding method wherein main current passage includes two or more electrode force application steps including a first electrode force application step and a second electrode force application step following the first electrode force application step, an electrode force F.sub.1 in the first electrode force application step and an electrode force F.sub.2 in the second electrode force application step in the main current passage satisfy a relationship F.sub.1>F.sub.2, and an electrode force switching point T.sub.f from the first electrode force application step to the second electrode force application step in the main current passage is set to satisfy predetermined relational formulas.

A method of joining dissimilar material pipes includes applying a brazing metal filler to an end of a first pipe, press-inserting the end of the first pipe, with the brazing metal filler applied, into a second pipe, and plastically deforming and joining overlapping plastic deformation portions of the first pipe and the second pipe in a joint assembly, where the first pipe is fitted to the second pipe. This method offers joined dissimilar material pipe, which provides improved sealing capacity and perform well under high pressure and extremely low temperatures.

The invention relates to a process for producing a pipe fitting (10), for example a reduction piece, a pipe elbow or a branch, wherein a metallic material (11) is melted by heating, and wherein a plurality of material layers (12) is produced in a successive manner from the melted material (11), wherein the in each case produced material layer (12) is materially bonded to the in each case previous material layer (12), and wherein the pipe fitting (10) is formed from the material layers (12) bonded to one another. The pipe fitting (10) is produced by buildup welding, for example arc welding or beam welding.

The present disclosure relates to electro-conduction devices and methods for submerged arc welding of straight-seam steel pipes and in particular to a lateral electro-conduction device and method for multi-wire submerged arc inner/outer welding of a straight-seam steel pipe. The present disclosure aims to overcome the problem of poor closing of the electromagnetic field resulting from the existing negative-pole electro-conduction mechanism and the problem of unstable welding process resulting from bending deformation in the steel pipe welding process. The device includes: a floating surface contact electro-conduction device, capable of forming a surface contact with an outer surface of the straight-seam steel pipe; a lateral electro-conduction brush device, including multiple electro-conduction brushes and electrically connected with the floating surface contact electro-conduction device; a lateral electro-conduction metal plate. electrically connected with a negative-pole wire harness of a welding machine and electrically connected with the lateral electro-conduction brush device.

An iron-based alloy composition including: boron (B): 1.6-2.4 wt. %; carbon (C): 1.7-3.0 wt. %; molybdenum (Mo): 16.0-19.5 wt. %; nickel (Ni): 3.5-6.5 wt. %; manganese (Mn): below 0.8 wt. %; silicon (Si): 0.2-3.0 wt. %; vanadium (V): 10.8-13.2 wt. %; and balanced with iron (Fe). Also, an item including a substrate portion and a hardfacing coating bonded to the substrate portion, wherein the hardfacing coating is made by an overlay welding process using the iron-based alloy composition.

To further improve electrodeposition coating properties in a weld bead zone. A welded joint according to the present invention includes: a first steel sheet and a second steel sheet; and a weld bead zone formed by arc welding or laser welding, wherein at least one of the first steel sheet or the second steel sheet has a plating layer composed of a predetermined component and an oxide layer located on the plating layer in a non-heat-affected zone, and the weld bead zone has a weld metal and a slag layer formed on part of a surface of the weld metal, and the slag layer contains, by mass % when oxygen is excluded, Al: 1.0 to 45.0% and Mg: 1.0 to 30.0%, with the balance composed of Fe, easily oxidizable metallic elements, and impurities.

A method of preparing a pipe-section for welding to another pipe-section to form a pipeline comprising a plurality of said pipe-sections, the method comprising at least the steps of: (i) providing a pipe-section having first and second pipe-ends; (ii) defining a first portion L1 of the longitudinal length of the pipe-section from the first pipe-end being in the range 3% to 40% of the overall length of the pipe-section; (iii) defining a second portion L2 of the longitudinal length of the pipe-section from the end of the first portion L1 towards the second pipe-end; (iv) heating at least the first portion L1 to at least a first temperature T1 of at least 500 C. for at least 2 minutes; (v) maintaining a second temperature T2 of the second portion L2 during step (iv) below the first temperature T1. The invention is able to reduce the strain capacity during reel-laying of a pipeline formed from a plurality of pipe sections formed by the invention.

An ultra-long steel strip grating manufacturing system using femtosecond laser with spatiotemporal parameters cooperative control, the manufacturing system comprising an unwinding roller, a traction roller and a winding roller, a linear femtosecond laser unit and an electronic shutter being disposed between the unwinding roller and the traction roller and directly above the electronic shutter, a cleaning unit being disposed between the traction roller and the winding roller, a first inspection unit being disposed between the cleaning unit and the winding roller, a second inspection unit being disposed directly above the winding roller, and a plurality of auxiliary roller systems which are driven rollers being disposed along a conveying direction of the steel strip, which achieves a horizontal movement of the steel strip under the electronic shutter, and also achieves a smooth entry of the steel strip into the cleaning unit for cleaning.

Intended is to improve the corrosion resistance of an overlay used in a nuclear power plant, and to reduce dissolution of cobalt from an overlay. The corrosion and wear resistant overlay 7 is formed along a surface of a base 2 by laser lamination modeling, and is configured from a plurality of metal layers 1a, 1b, 1c, and 1d of a Co-base alloy. The thickness of carbide eutectics that precipitate in the metal layers 1a, 1b, 1c, and 1d is the largest in the metal layer 1a closest to the base 2, and is gradually smaller in the metal layers 1b, 1c, and 1d farther away from the base 2. The intensity of the laser beam applied to form layers by laser lamination modeling is adjusted so that the carbide eutectics that precipitate in at least the outermost metal layer 1d have a controlled size of 10 m or less.

The invention relates to a method for additive manufacture of a workpiece under protective gas, wherein a workpiece is assembled from a sequence of workpiece contours, each of which is manufactured by selective sintering or melting of a powdery or wire-like material by applying an energy beam thereto, wherein a workpiece contour is manufactured under the effect of a protective gas consisting of carbon dioxide and an inert gas. According to the invention, the chemical composition of each workpiece contour is modified according to a specified program by variation of the composition of the protective gas. Heat treatment occurring after manufacture of the workpiece contour provides for defined mechanical and technological quality values of the workpiece contour. A workpiece having zones with defined mechanical and technological quality values is produced in this manner.